ORIGINAL PAPER Modeling of Wheat Straw Torrefaction as a Preliminary Tool for Process Design N. Nikolopoulos • R. Isemin • K. Atsonios • D. Kourkoumpas • S. Kuzmin • A. Mikhalev • A. Nikolopoulos • M. Agraniotis • P. Grammelis • Em. Kakaras Received: 24 July 2012 / Accepted: 15 January 2013 Ó Springer Science+Business Media Dordrecht 2013 Abstract Torrefaction is considered as a kind of mild pyrolysis that is carried out under inert atmosphere (usually nitrogen) conditions. During this process, the moisture of the initial fuel and a portion of its volatiles are removed from the biomass particles towards the inert atmosphere. The resulted torrefied solid biomass has high energy density, durability and less hydrophilic character. The most benefi- cial result of torrefaction process is that biomass feedstock logistics cost can be reduced, as less tones of biomass are required for a given amount of energy input. The develop- ment of a process model examining basic parameters as reaction temperature and residence time can provide useful information, which can be used for the more efficient design of a torrefaction reactor. This study presents such a process model for a straw torrefaction pilot plant. This model is based on the thermodynamic calculation of a single and/or a two batch reactor, built on the commercial software ASPEN Plus. The calculation of required flow rates of inert gas, cooling medium for a specific biomass feedstock value, is based on relevant results found in literature. Keywords Wheat straw  Torrefaction  Thermodynamic modeling  ASPEN Plus List of symbols C p Heat capacity coefficient (J/kg K) E Activation energy (J/mol K) M Mass yield (kg) K Kinetic rate (1/s) t Time (s) t heat Heating time required for achievement of torrefac- tion temperature (s) t* Critical time at which the second stage of torrefaction begins and dominates over the first one (s) N. Nikolopoulos  K. Atsonios  D. Kourkoumpas  A. Nikolopoulos  P. Grammelis  Em. Kakaras Centre for Research and Technology Hellas, Chemical Process & Energy Resources Institute (CERTH/CPERI), Athens, Greece e-mail: atsonios@certh.gr D. Kourkoumpas e-mail: kourkoumpas@certh.gr A. Nikolopoulos e-mail: a.nikolopoulos@certh.gr P. Grammelis e-mail: grammelis@certh.gr Em. Kakaras e-mail: ekak@central.ntua.gr N. Nikolopoulos (&) ARKAT Building, 357-359 Mesogeion Ave., Halandri, Athens, Greece e-mail: n.nikolopoulos@certh.gr R. Isemin  S. Kuzmin  A. Mikhalev Tambov State Technical University, Tambov, Russia e-mail: risemin@gmail.com S. Kuzmin e-mail: admin@ido.tstu.ru A. Mikhalev e-mail: admin@ido.tstu.ru K. Atsonios  A. Nikolopoulos  Em. Kakaras Laboratory of Steam Boilers and Thermal Plants, National Technical University of Athens, Athens, Greece M. Agraniotis Clean Energy Ltd., 4th km Ptolemais-Mpodosakeiou, Ptolemais, Greece e-mail: agraniotis@certh.gr 123 Waste Biomass Valor DOI 10.1007/s12649-013-9198-y